One of the propellant combinations that Tsiolkovsky favored, used commonly today in launch vehicles, was liquid hydrogen and liquid oxygen because it produces a particularly high exhaust velocity. This factor, the rocket equation reveals, helps determine the maximum speed that a spacecraft of given mass can reach. There was the problem of converting hydrogen, especially, into liquid; yet, to begin with, Tsiolkovsky brushed this aside. He did note, however, that: “The hydrogen may be replaced by a liquid or condensed hydrocarbon; for example, acetylene or petroleum.”

His rocket equation led him to another important realization: If a single-stage rocket is to attain cosmic velocity it must carry an immense store of fuel. Thus, to reach the first cosmic velocity [his term for the speed needed to enter Earth orbit], 8 km/s, the weight of fuel must exceed that of the whole rocket (payload included) by at least four times... The stage principle, on the other hand, enables us either to obtain high cosmic velocities, or to employ comparatively small amounts of propellant components.The concept of the multistage rocket had been known to firework-makers for at least two centuries. But Tsiolkovsky was the first to analyze it in depth, and he concluded that it was the only feasible way of enabling a spacecraft to escape from the Earth’s gravity.

Von Braun selected nitric acid/hydrazine propellants, perhaps as a result of the same Peenemuende research that influenced the French team. Von Braun made significant advances in refining Rocket Design over the years.